Drug & supplement interaction

Ilex Guayusa + Fluconazole

Fluconazole brand names: Diflucan, Diflucan Injection.

Minor Interaction
Medically reviewed by · Updated September 2026
The bottom line Minor

Ilex Guayusa has a minor interaction with Fluconazole. Theoretically, fluconazole might increase the levels and adverse effects of caffeine.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Ilex Guayusa and Fluconazole

Here is the interaction we found between these two, with the evidence behind it.

Minor

FLUCONAZOLE (Diflucan)

Theoretically, fluconazole might increase the levels and adverse effects of caffeine.
Ilex guayusa contains caffeine. Fluconazole decreases caffeine clearance by approximately 25%.
Severity Minor Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know about pairing guayusa tea with fluconazole: it's really the caffeine in guayusa that matters, not the fluconazole itself. Fluconazole slows down how fast your body clears caffeine, by roughly a quarter. So the same cup of guayusa may hit harder and linger longer while you're on this antifungal.

In practice, that can mean more of the usual caffeine effects, like feeling jittery, a racing or pounding heartbeat, trouble sleeping, or an upset stomach. This is a minor interaction and partly theoretical, so most people do fine. If you notice you're wired or sleepless, simply cutting back on guayusa usually fixes it. Check with your pharmacist or doctor if you have heart concerns.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Nix D, Zelenitsky S, Symonds W, et al. The effect of fluconazole on the pharmacokinetics of caffeine in young and elderly subjects. Clin Pharmacol Ther 1992;51:183. DOI
  2. Zelenitsky SA, Norman A, Nix DE. The effects of fluconazole on the pharmacokinetics of caffeine in young and elderly subjects. J Infect Dis Pharmacother 1995;1:1-11.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Ilex Guayusa Also Interacts With Other Medications

Ilex Guayusa has 8 major, 470 moderate, 126 minor known drug interactions in our database — the Fluconazole one above is one of them. If you take anything else, check it against the full list below.

Major 8 Moderate 470 Minor 126 No known interaction 2,226 (incl. Fluconazole)
Taking anything else?

Check Another of Your Medications Against Ilex Guayusa

Covers the 2,830 medications we’ve checked against Ilex Guayusa. Pick one to open its full report.

From our Q&A

Questions About Ilex Guayusa or Fluconazole

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Ilex Guayusa or Fluconazole, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Fluconazole

This page covers Ilex Guayusa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fluconazole page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Adrafinil (moderate).

By severity: 4 major · 54 moderate · 23 minor.

From our pharmacist’s overview on the Fluconazole page

“Fluconazole (Diflucan) treats fungal infections, and I would pair it with supplements carefully. Nearly half of the 81 ingredients with an interaction on file, 38 of them, put extra strain on the liver, which is already busy processing the antifungal.”

Reviewed by 2 · Jul 18, 2026

Open the Fluconazole interaction page

How much people look this up

Where Ilex Guayusa and Fluconazole Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Ilex Guayusa
Steady interest

#1,135 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Fluconazole
Top 25%

#385 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Ilex Guayusa

What is Ilex Guayusa?

  • Energy and alertness
  • Mental focus
  • Antioxidant support
  • Appetite control
  • Athletic and physical performance

Ilex guayusa is a caffeine-containing holly leaf from the Amazon, traditionally brewed as a tea for energy and alertness, much like yerba mate or green tea. There is limited human research confirming specific health benefits, and its main reliable effect comes from its caffeine content. Because it is a stimulant, use it cautiously and check with your pharmacist or doctor if you have heart concerns or are pregnant.

Read the full Ilex Guayusa monograph & all interactions
Medication

About Fluconazole

What Is Fluconazole Used For?

Brand names: Diflucan, Diflucan Injection

Fluconazole treats infections caused by Candida and Cryptococcus fungi. Diflucan tablets and oral fluconazole tablets and suspension are approved to treat vaginal yeast infections (vaginal candidiasis), thrush in the mouth or throat (oropharyngeal candidiasis), and yeast infections of the esophagus. All forms — tablets, oral suspension, and injection — are used for cryptococcal meningitis (a serious fungal brain infection). In smaller studies, fluconazole has also shown effectiveness against Candida urinary tract infections, peritonitis (infection in the abdomen), and serious systemic (bloodstream and organ) Candida infections.

Fluconazole is also used to prevent candidiasis in people undergoing bone marrow transplants who receive chemotherapy or radiation therapy. Note that vaginal candidiasis is an approved use for the tablets and Diflucan oral products, but not for the injection or oral suspension alone.

See full Fluconazole drug information
Keep checking

Other Drugs & Ilex Guayusa

Browse every other medication we’ve checked against Ilex Guayusa — both the ones with a known interaction and the ones without. Select any drug for the full detail.

8Major
470Moderate
126Minor
2,225No known interaction
8 Major 470 Moderate 126 Minor 2,225 No interaction
Major

8 interactions

Moderate

470 interactions

Showing 60 of 470 moderate interactions — see all 470 on the Ilex Guayusa page.

Minor

126 interactions

Showing 60 of 126 minor interactions — see all 126 on the Ilex Guayusa page.

No interaction 2,225 drugs checked — show the list

We also checked Ilex Guayusa against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,225 medications checked with no known interaction — see the full Ilex Guayusa list.

See the full Ilex Guayusa interactions page
See every supplement checked against Fluconazole, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Ilex Guayusa monograph › Uses, safety, and every drug interaction in one place Fluconazole supplement interactions › Every supplement checked against Fluconazole, ranked by severity Fluconazole drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Ilex Guayusa and Fluconazole Together: Common Questions

Can you take Ilex Guayusa with Fluconazole?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Ilex Guayusa and Fluconazole interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Fluconazole and Ilex Guayusa?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.